Question

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Part 1
The brain volumes ​(cm3​) of 50 brains vary from a low of 904 cm3 to a high of 1488 cm3. Use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 156.9 cm3​, assuming the estimate is accurate if it is within 15 cm3.
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Part 1
The estimated standard deviation is enter your response here cm3.
​(Type an integer or a decimal. Do not​ round.)

Answer 1

The range rule of thumb states that the estimated standard deviation s is approximately equal to the range divided by 4.

Range = 1488 - 904 = 584 cm3

Therefore, the estimated standard deviation s is approximately:

s = Range / 4 = 584 / 4 = 146 cm3

The given exact standard deviation is 156.9 cm3.

Since the estimate is within 15 cm3 of the exact standard deviation, we can say that the estimate is accurate.